Electric steam boiler



J. L. HALL, JR., ETAL 2,559,954

ELECTRIC STEAM BOILER 2 Sheets-Sheet l July 10, 1951 Filed July 14, 1947 INVENTORS.

I JOHN LJ/ALLJ ATTORNEY PRESSl/R ca/vrmL sw/rcw July 10,, 1951 J. L. HALL, JR., EITAL ELECTRIC STEAM BOILER 2 Sheets-Sheet 2 Filed July 14, 1947 4 I lax; ATTORNEY Patented July 10, 1951 OFFICE ELECTRIC STEAM BOILER John L. Hall, Jr., and Theron D. Whidden, Sr., Jacksonville, Fla.

Application July 14, 1947, Serial No. 760,784

7 Claims.

This invention relates to steam boilers and more specifically to electric steam boilers of the flash type.

It is an object of this invention to provide an improved electric steam boiler of the flash type, that is, one which generates steam very quickly.

It is another object of the invention to provide an improved electric steam boiler of the flash type in which the electric heating elements can be quickly and easily removed for replacement or repair.

It is a further object of this invention to p ovide an electric steam boiler which generates steam faster than other boilers of this type, which is simple and cheap to operate, maintain and repair, and has a long life.

It is still another object of this invention to provide an electric steam boiler utilizing a number of electric heating elements with individual pressure controlled switching means therefor.

Other objects and features of the invention, some of them more or less related to those already stated above, Will be apparent from the following description and the appended claims.

The above and related objects are attained in accordance with the invention by providing a main steam boiler having one or more tubes or chambers of relatively small cross-sectional area associated therewith, each of the tubes or chambers being connected at the top and bottom with the main boiler and being provided with electric heating means which can be easily removed for replacement or repair. Each tube is of very small cross-sectional area compared with that of the main boiler (say, for example, less than onetenth of the area of the latter.) Each heater can be controlled by its own manually-controlled switch or it can be provided with its own pressure-controlled switching means. Preferably, as the pressure drops, one heater element at a time is energized. The boiler arrangement in accordance with this invention can be made entirely automatic or it can be manually operated.

The invention will be more readily understood by referring to the following description taken in connection with the accompanying drawings forming a part thereof, in which:

Fig. 1 is a front elevation view of a flash electric steam boiler in accordance with this invention;

Fig. 2 is a cross-sectional side elevation View of the arrangement shown in Fig. 1;

Fig. 3 is a top vie of the arrangement of Fig. 1;

Fig. 4 is a horizontal cross-sectional view taken in a plane through line 4-4 of Fig. 2;

Fi 5 is a horizontal cross-Sectional view taken Fig. 6 is a top view, with portions broken away, of an arrangement similar to that of Fig. 1 except that two instead of four heating chambers are provided therein; and

Fig. '7 is an electric circuit in accordance with the invention showing four pressure-controlled switches each controlling its individual heating element.

Referring more specifically to the drawings, Figs. 1 and 2 show, by way of example for purposes of illustration, a flash type electric steam boiler iii in accordance with the invention. This comprises a main boiler compartment ll consisting of a steel tube or cylinder 12 with top and bottom members 13 and i l, respectively, welded or otherwise secured thereto. The boiler H is supported from less I5, or by other suitable means, from the floor, the legs being long enough so that the heating elements [6, to be later described, can be put in or pulled out without removing the boiler from the legs. The boiler II is adapted to have a low water line, preferably somewhere between the line I! which is above the top of the elements It and the higher line l3 which is still well below the middle of the boiler I i. Outside the boiler II are a plurality of tubes or restricted chambers l9 (four are shown in Figs. 1 to 5 inclusive) each of which has a crosssectional area less than one-tenth that of the boiler ll. They are connected to the boiler at both top and bottom. Preferably each tube 19 has a heating element 16 in the lower portion thereof. Each element i6 is attached to an element flange 20 Which is bolted or otherwise secured to the tube flange. An electrical connection (see Fig. 7) is made to each element [6 by means of lines 21 which are connected through individual manually operated switches 22 to a power cable or pair of lines 23. One or more electric pressure control switches 24 may be used to apply electric power to the heater elements I 6. As shown in Fig. 7, individual pressure control switches 26 can be provided, one for each element F 6. If desired, they can be set to operate at different pressures. Thus, for example, if the boiler operates at 50 lb. maximum pressure, as the pressure drops, one switch (P. C. #l) is set to turn on one element [6 at 45 1b., a second switch (P. C. #2) to turn on another element [6 at 42 1b., a third switch (P. C. #3) to turn on a third element I6 at 40 lb. and a fourth switch (P. C. #4) to turn on the fourth element at 38 lb. All pressure control switches are cut oil at maximum boiler pressure. When the manual switches are being used, the pressure control switches are left open and when the latter are being used the manual switches are left open.

Water is admitted to the boiler by pipe 25 and steam taken therefrom by pipe 26 which is at the top of the boiler ll. Any suitable means, such as a boiler water feeder and boiler water feed pump and water level control member, can be used to make the flow of water automatic when the lower water level line it is reached and to shut off the water when the upper water level line I8 is reached. As these elements are well known in the art they will not be shown or described in detail here.

Any suitable water level gauge 2'! can be used. A pressure gauge 28 is provided at the top of the boiler and one or more pop-off valves of any suitable type are provided for, safety purposes. One can be located near the gauge 28. Inspection for sediment or scale can be made by removin the blowoff cocks 29.

- Instead of four tubes i9, two can be provided, as shown in Fig. 6, or any other desired number can be used.

The boiler arrangement in accordance with this invention has many advantages. The small volume of water around each element it allows quick steaming but there is an ample supply as the water will equalize in height with that in the main boiler compartment ii. The water in the compartment il will remain cold for some time even after the steam pressure has been raised because the water in the large boiler chamber ii is heated only by contact with the steam. Even after all the water in the boiler H has been heated and it becomes necessary to add water, this cold water does not reduce the steam pressure. Mistreatment such as operating with low water or not treating the water with chemicals to reduce carbohydrates that cause scale in boiler or not blowing off the boiler or not cleaning the boiler will not cause damage to the main boiler compartment Ii. Any of these mistreatments may damage the heating element or elements it but the cost of replacing any new elements and cleaning out the element tubes 19. is minor compared to repairs on the ordinary type boilers. This boiler cannot be blown apart from pressure caused by low water, as there is no external heat on the plates of the boiler. If water has been out of the boiler for some time and cold water were turned into it, the small heatin area of the elements it cannot suddenly make steam pressure that the relief valve cannot handle.

This is an ideal type of boiler to install in units or banks as the steam valve between the boiler unit and the main steam line can be closed and repairs made on the damaged unit while other boiler units are still operating.

- In an actual test, all water was drained from the hot boiler through the blowoff cocks 29 and it was refilled with cold water (approximate tem perature 50 degrees) to the top of the water gaug 21. While the boiler was still hot, the switches were turned on and almost instantly the steam pressure gauge had the same climb per minute as before the water was changed.

Various modifications can be made in the embodiments described above without departing from the spirit of the invention, the scope of which is indicated in the appended claims.

What is claimed is:

1. A flash electric boiler comprising a main boiler compartment, a chamber outside said compartment and connecting into it at both its top and bottom portions, said chamber having a horizontal cross-sectional area which is less than one-tenth that of said compartment, an electric heating element in the lower part only or said chamber, means for filling said compartment and hence said chamber with water to a level above the top of said heatin element but well below the middle of said compartment, and an outlet in the upper portion of said compartment above the upper connection from said chamber and separated from said connection for taking steam from said chamber and said compartment to a heating system.

2. A flash electric boiler comprising a main boiler compartment, a tube outside said compartment and connecting into it at both its top and bottom portions, said tube having a horizontal cross-sectional area which is less than one-tenth that of said compartment, an electric heating element in the lower part only of said tube, means for filling said compartment and hence said tube with water to a level above the top of said heating element but below the middle of said compartment, and an outlet in the upper portion of said compartment above the upper connection from said tube and separated from said connection for taking steam from said tube and said compartment to a heating system.

3. A flash electric boiler comprising a main boiler compartment, a plurality of tubes outside compartment, each tube connecting into the compartment at both its top and bottom portions and each having a horizontal cross-sectional area which is less than one-tenth that of said compartment, an electric heating element in the lower part only of each tube, means for filling said compartment and hence said tubes with water to a level above the top of said heating elements but below the middle of said compartment, and means in the upper portion of said compartment and separated from the upper connections from said tubes for taking steam therefrom.

4. A flash electric boiler comprising a main boiler compartment, a plurality of tubes outside said compartment, each tube connecting into the compartment at both its top and bottom portions and each having a horizontal cross-sectional area which is less than one-tenth that of said compartment, an electric heating element in the lower part only of each tube. means for filling said compartment and hence said tubes with water to a level above the top of said heating elements but below the middle of said compartment, and means in the upper portion of said compartment and separated from the upper connections from said tubes for taking steam therefrom, said tubes being equally spaced around the outside of said main boiler compartment.

5. A flash electric boiler comprising a main boiler compartment, a tube outside said compartment and connecting into it at both its top and bottom portions, said tube having a horizontal cross-sectional area which is less than one-tenth that of said compartment, an electric heating element in the lower part only of said tube, means for filling said compartment and hence said tube with water to a level above the top of said heating element but below the middle of said compartment, and an outlet in the upper portion of said compartment above the upper connection from said tube and separated from said connection for taking steam from said tube and said compartment to a heating system, said tube being provided with means at the bottom thereof whereby said heating element can be removed therefrom.

6. The combination of elements as in claim 5 in further combination with means for supporting said main compartment and tube a distance above the floor at least as great as the length of said heating element.

7. A flash electric boiler comprising a main boiler compartment, a plurality of tubes outside said compartment, each tube connecting into the compartment at both its top and bottom portions and each having a horizontal cross-sectional area which is less than one-tenth that of said compartment, an electric heating element in the lower part only of each tube, means for filling said compartment and hence said tubes with water to a level above the top of said heating elements but below the middle of said compartment, and means in the upper portion of said compartment and separated from the upper connections from said tubes for taking steam therefrom, said heating elements having separate pressure-controlled circuits so that they can be switched on at diiferent times depending on the pressure.

JOHN L. HALL, JR.

THERON D. WHIDDEN, SR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

